All: I am trying to tune my new 70 GS350 and having trouble with ignition timing. I did the following: 1) Checked the dwell with meter and it is 30 degrees per emission decal 2) I plugged the vacuum advance hose w/ golf tee and capped the carb port 3) I then set idle per decal to 625 PRM with engine warm 4) I put brand new Sears timing gun lead on plug wire closest to oil fill (driver side front) and connected clips to positive battery and black to AC bracket. Problem: The lit timing mark is well past all timing measures cast into the block. It is so advanced past the marks I thought the gun was bad. I then noticed the lit mark facing the hood rather than me. If I try to adjust the iginition by rotating the distributor the correcting direction, the motor dies. Should I presume the distributor is installed a tooth or two off? The car has had trouble running since it came off the trailer. I think I chased away the carberator boogey man with the 750 JO Carb I put on. Now the timing gremilin has got me.o No:
the distributor being a tooth off won't show up in the timing since you can rotate the dist where it needs to be. Do you have a dial back timing light? If so, set the dial to the desired timing and turn the dist until the timing mark on the balancer is aligned with zero on the timing cover. If it's not a dial back timing light you turn the dist until the mark on the balancer aligns with the desired number on the timing cover. If it won't run right when you do this the outer part of the balancer may have moved. I've personally never seen it happen but I hear it does. This assumes your ignition is right. Since you said it has had trouble running, you will want to check the distributor cap and rotor.
if it has not driven right since you got it, i would check points cap rotor and turn the dist till it matches the tag. try about 8 btdc to start. remember you have purchased a OLD new car. who knows what was done before you got it. step back relax and check every thing. good luck jim ps normally the dist opening for dwell is straight to the front or at 5pm to 7pm.
Please don't think me argumentative (anyone please), as I am trying to learn. So I will ask more ??s If the dwell checked out, can I conclude the points are good? They look new as well as the rotor. I wonder if a tune-up attempt went bad.....but where?
Not necessarily; 30* just means they are adjusted correctly. If they are not worn too much and both surfaces are smooth, take an emery board and run it across the contacts first to be sure. Points are VERY reliable and are probably not the problem. Make sure the condenser bracket is grounded to the distributor plate if it's not attached to the points. Look at the cap contacts and clean if necessary. Check it for any cracks. Make sure the firing order is right. (None of this affects the timing.) Put a vacuum gauge on the full vacuum port and adjust the timing for max vacuum. That will get you very close to what it should be. Put the light on it and let us know what the timing reads.
First, the distributor is not one tooth off as you can adjust the timing, it's just that the engine will not idle when you do. The problem is that you do not know the history of this car and engine as you have just purchased it. More important than initial timing is total timing. I encourage you to read this timing thread I wrote many years ago. http://www.v8buick.com/showthread.php?t=63475 The stock timing tab only goes up to 12* BTDC. The mark appears beyond this, so your initial timing is more than 12*. The more initial advance you have, the less throttle opening you need to maintain an idle. I would try increasing the idle speed before you try to adjust the timing. The stock specs for a 70 GS 350 is 6* BTDC. That is if the engine has the original distributor, and that is a big IF, these cars are 38 years old, and lots of things can happen in 38 years. See if you can read the numbers on the distributor, that will narrow things down. It is possible that the timing mark on the balancer has slipped. It is unlikely, but it happens occasionally. You can check it with a piston stop. Another possibility is you have a vacuum leak somewhere. An engine with a vacuum leak will want alot of advance to idle. Again, these engines are 38 years old, lots can happen. Sometimes during a rebuild, the block and/or heads are resurfaced, and the intake does not fit correctly resulting in a vacuum leak into the valley. This has happened to several guys on this BB. Do you have an advance timing light or a regular light? Do you know the difference? Hope I can help.
Larry: Thanks to you and all for helping. I have your original post in hand and read it a number of times. However, it seemed the tone was peak performance. I just want it to run so I felt simpler was initially better (ie tune to emission sticker specs.) I do have a dial back Sears unit per your advice. I tried to buy a vacuum gauge this PM but Autozone was out of stock. I will stop at Sears this week and pick one up. I will check the distributor for originality also. Your vacuum leak scenario seems the most likely. Thanks!
make sure you eyeball the guts of dist. the points can be made to go to 30 and still be a little off and worn. the inside of cap could be burnt or as said before cracked. just do not be like me and get in a hurry. i have to keep my temper down and rethink things. usually it will take 20 hours of reading for about 15 min of actual work. best of luck jim
What cam do you have?. A stock motor should pull at least 18-20" at idle in Park If the distributor is not the original one that belongs in the car, the initial timing on the emissions sticker goes right out the window. Performance tuning has no downside, the engine will run better, have more power, and get better gas mileage. Set the total timing. The initial falls where it falls.
I did plug the vacuum advance when I tried to set initial timing but I did not try it w/o it plugged. I will try it both ways to see if there is an impact. I suppose if there is no variance in timing readings plugged v unplugged it could mean the v advance is bad (leaks?) I did note a fuel leak along the frame rail near the driver's door when I came home last night. My Toyota ran crappy when it had a leaking supply line. However, I can't say either way if the leak problem would show up in timing measurements.
Get the fuel leak fixed now. That is dangerous. The leak is probably one of the two rubber lines in the location you described. They are short chunks of line that connect the front hardlines to the rear. They are located inside the frame rail. One line is 3/8th the other is 1/4th. It is possible that you could be sucking air there and not getting enough fuel.
hook the vacuum gauge to the lowest point on the carb. since your car is a 63? it will be the same as the vacuum adv hose goes to. plug the vac adv as you stated before. then adj the timing to get high vacuum. then check with the light. i bet it will be lower on the mark around 12 btdc or maybe 10. keep going you will get it.
Thanks for the 411. Can you estimate the length of each rubber line so I can grab them on the way home?
My car is a 70 using a 73 carb. Is that relevant for which source of vacuum I choose? I imagine the line that drives the v advance will be a good choice no matter what application.o No:
My friends 455 had this happen. You can check it by taking the valve spring off a #1 cylinder valve and letting it drop to the piston (make sure the piston is at the top). Then put a dial gauge on the valve stem. Mark the balance .050 from TDC and .050 past TDC and the spot in the middle is the actual TDC.
Apparently the anatomy of a balancer is different than I presumed. The outer ring w/ engraved timing mark must be insulated totally from the crank via the rubber portion. If all remedies fail, I will investigate the balancer theory
